Differences in master cylinders....
A partial quote:
A four wheel disc brake master cylinder is designed to supply more fluid pressure and volume to the rear disc brakes than the disc / drum master does. This is acheived through an internal piston re design. The piston that feeds the rear brakes on a disc / drum master will run out of stroke, limiting the amount of fluid pressure and volume that may be supplied to the rear isc brakes.
The four wheel disc master re design delivers the extra needed volume and pressure to the rear allowing your rear disc brakes to function properly. If you attempt to use a disc/drum master on a four wheel disc system you will get poor rear brake function and experience a spongy brake pedal with a long pedal travel. -
I've never heard of such a thing.
The rear piston of a tandem master is directly actuated by the pedal pushrod, and this is hooked to the front brakes on either a disk drum or a disk disk system, so how is a "piston redesign" going to affect internal pressure in the master"
Let me once again dispel this myth...................IF THE MASTER BORE is of the correct bore SIZE to give you the right "leg ratio" for overall pressure to stop the thing, and IF you watch the fluid level over a reasonable length of time AKA "months" once you set the system set up, bled, and shoes adjusted, the reservoir size is not material whether disk /drum or disk disk. The large disk reservoir was for "us idiots," that is, "us idiots" who buy our cars, drive our cars for 100K miles without ever thinking of checking anything on them as you know there are those of us who do
So to repeat myself once again............
I have the little bitty 67 master, the ORIGINAL 9" drum-drum master on mine which runs the 74 Duster disks, and Versailles rear disks, and this gets me maybe 25%? to maybe 35% this is just a guess or so of pedal stroke? to a hard pedal and the thing STOPS.
So the point is that this idea that disk brakes "USE" so much fluid is so much malarky.
